Neuroendocrine tumors of the genital tract.

Neuroendocrine tumors are more common in the female than male genital tract; most are uterine small cell carcinomas or ovarian carcinoids. Primary ovarian carcinoids are divided into insular, trabecular, strumal, and mucinous types; most are benign. Carcinoids metastatic to the ovary are more aggressive; most arise in the gastrointestinal tract. Scattered neuroendocrine cells are seen in a variety of ovarian surface epithelial tumors; sporadic mucinous cystic tumors with neuroendocrine cells have been associated with Zollinger-Ellison syndrome. Frank neuroendocrine carcinomas in the ovary include small cell carcinoma and large cell neuroendocrine carcinoma, each with a poor prognosis and often associated with a conventional surface epithelial tumor Such carcinomas also occur in the endometrium and cervix. Uterine carcinoids are rare if strict criteria are applied. Small cell neuroendocrine carcinomas also occur rarely in the vagina and vulva. Most male genital tract neuroendocrine tumors are prostatic small cell carcinomas or testicular carcinoids. Extragonadal carcinoids of the male genital tract are rare. Testicular carcinoids should be distinguishedfrom metastatic tumors. It is important to distinguish prostatic small cell carcinoma from poorly differentiated adenocarcinoma with small cells. Small cell neuroendocrine carcinomas also occur rarely in the scrotum, penis, and penile urethra.